U.S. patent application number 16/561646 was filed with the patent office on 2020-01-02 for thermally activated strong acids.
The applicant listed for this patent is SHELL OIL COMPANY. Invention is credited to Robert Lawrence BLACKBOURN, Lee Nicky MORGENTHALER, Ryan Matthew VAN ZANTEN, Paul Richard WEIDER, Ying ZHANG.
Application Number | 20200003040 16/561646 |
Document ID | / |
Family ID | 51904289 |
Filed Date | 2020-01-02 |
United States Patent
Application |
20200003040 |
Kind Code |
A1 |
WEIDER; Paul Richard ; et
al. |
January 2, 2020 |
THERMALLY ACTIVATED STRONG ACIDS
Abstract
An acid-generating fluid includes a thermally activated strong
acid precursor. The thermally activated strong acid precursor can
include a component selected from aldehydes, ketones, and
combinations thereof, in combination with a precursor of a compound
adapted to react to liberate sulfur dioxide; or it can include
sulfur dioxide in combination with a precursor of a compound
adapted to react to liberate a component selected from aldehydes,
ketones, and combinations thereof.
Inventors: |
WEIDER; Paul Richard;
(Houston, TX) ; BLACKBOURN; Robert Lawrence;
(Houston, TX) ; ZHANG; Ying; (Sugar Land, TX)
; MORGENTHALER; Lee Nicky; (Houston, TX) ; VAN
ZANTEN; Ryan Matthew; (Katy, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SHELL OIL COMPANY |
HOUSTON |
TX |
US |
|
|
Family ID: |
51904289 |
Appl. No.: |
16/561646 |
Filed: |
September 5, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15667779 |
Aug 3, 2017 |
10443368 |
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16561646 |
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15034619 |
May 5, 2016 |
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PCT/US2014/063993 |
Nov 5, 2014 |
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15667779 |
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61901098 |
Nov 7, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C09K 8/506 20130101;
C09K 8/72 20130101; E21B 43/36 20130101; E21B 43/25 20130101; C09K
8/516 20130101 |
International
Class: |
E21B 43/36 20060101
E21B043/36; C09K 8/506 20060101 C09K008/506; C09K 8/516 20060101
C09K008/516; C09K 8/72 20060101 C09K008/72; E21B 43/25 20060101
E21B043/25 |
Claims
1. A method comprising: providing an acid-generating fluid that
comprises water and a thermally activated strong acid precursor,
the thermally activated strong acid precursor comprising: a
precursor of a compound adapted to react to liberate sulfur
dioxide, and a component selected from aldehydes, ketones, and
combinations thereof; placing the acid-generating fluid into a
subterranean formation; thermally activating the precursor, thereby
liberating sulfur dioxide; and reacting the sulfur dioxide and the
component selected from aldehydes, ketones, and combinations
thereof to form a thermally activated strong acid.
2. The method of claim 1, wherein the precursor is selected from
the group consisting of a sulfone adduct of: butadiene, a sulfone
adduct of piperylene, a sulfone adduct of isoprene, a sulfite
ester, and combinations thereof.
3. The method of claim 1, wherein the first precursor is selected
from the group consisting of: ethylene sulfite and dimethyl
sulfite, and combinations thereof.
4. The method of claim 1, wherein the acid-generating fluid further
comprises a dienophile.
5. The method of claim 4, wherein the dieneophile and the thermally
activated strong acid precursor are provided in a 1:1 molar
ratio.
6. The method of claim 1, wherein the acid-generating fluid further
comprises a base.
7. The method of claim 6, wherein the base is CaCO.sub.3.
8. The method of claim 1, wherein the acid-generating fluid is an
emulsion.
9. The method of claim 1, wherein the acid-generating fluid has a
pH of greater than 4.
10. The method of claim 1, wherein the acid generating fluid is a
component of a fluid loss control pill.
11. A method comprising: providing an acid-generating fluid that
comprises water and a thermally activated strong acid precursor,
the thermally activated strong acid precursor comprising: sulfur
dioxide, and a precursor of a compound adapted to react to liberate
a component selected from aldehydes, ketones, and combinations
thereof; placing the acid-generating fluid into a subterranean
formation; thermally activating the precursor, thereby liberating
the component selected from aldehydes, ketones, and combinations
thereof; and reacting the sulfur dioxide and the component selected
from aldehydes, ketones, and combinations thereof to form a
thermally activated strong acid.
12. The method of claim 11, wherein the precursor is selected from
the group consisting of: paraformaldehyde, polyoxymethylene,
metaldehyde, trioxane, formaldehyde, acetaldehyde, and combinations
thereof.
13. The method of claim 11, wherein the acid-generating fluid
further comprises a dienophile.
14. The method of claim 13, wherein the dieneophile and the
thermally activated strong acid precursor are provided in a 1:1
molar ratio.
15. The method of claim 11, wherein the acid-generating fluid
further comprises a base.
16. The method of claim 15, wherein the base is CaCO.sub.3.
17. The method of claim 11, wherein the acid-generating fluid is an
emulsion.
18. The method of claim 11, wherein the acid-generating fluid has a
pH of greater than 4.
19. The method of claim 11, wherein the acid generating fluid is a
component of a fluid loss control pill.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a Divisional application of
application Ser. No. 15/667,779 filed Aug. 3, 2017, which is a
Continuation application of application Ser. No. 15/034,619, filed
on May 5, 2016 and Abandoned, which is a National Stage (.sctn.
371) of International Application No. PCT/US2014/063993, filed Nov.
5, 2014, which claims priority from U.S. Application No.
61/901,098, filed Nov. 7, 2013, the disclosures of each of which
are hereby incorporated by reference in their entirety.
BACKGROUND
[0002] The present disclosure relates generally to thermally
activated strong acids. More specifically, in certain embodiments,
the present disclosure relates to compositions capable of
generating strong acids downhole and associated methods.
[0003] Acid treatments using aqueous acidic solutions commonly are
carried out in subterranean formations. These acid simulations may
be used to accomplish a number of purposes. Such purposes may
include increasing or restoring the permeability of subterranean
formations so as to facilitate the flow of oil and gas from the
formation into the well. The acid treatments may be used to remove
formation damage along as much of the hydrocarbon flow path as
possible and/or to create new flow paths as in matrix
acidization.
[0004] Generally, in acidizing treatments, aqueous acidic solutions
are introduced into the wellbore or subterranean formation under
pressure so that the acidic solution flows into the wellbore or
pore spaces of the formation. Within the wellbore, the acidic
solution may also remove wellbore damage and filter cake. Within
the near-well formation, the acidic solution may remove near-well
formation damage and other damaging substances. In the near-well
formation, the acidic solution may react with acid-soluble
materials contained in the formation which results in an increase
in the size of the pore spaces and an increase in the permeability
of the formation. This procedure commonly enhances production by
increasing the effective well radius. Examples of such methods are
disclosed in U.S. Pat. No. 7,795,186, the entirety of which is
hereby incorporated by reference.
[0005] Although acidizing a portion of a subterranean formation can
be very beneficial in terms of permeability, conventional acidizing
systems have significant drawbacks. One major problem associated
with conventional acidizing treatment systems is that deeper
penetration into the formation is not usually achievable because,
inter alia, the acid may be spent before it can deeply penetrate
into the subterranean formation. Another problem associated with
acidizing subterranean formations is the corrosion caused by the
acidic solution to any metal goods (such as tubular goods) in the
well bore and the other equipment used to carry out the treatment.
For instance, conventional acidizing fluids, such as those that
contain organic acids, hydrochloric acid or a mixture of
hydrofluoric and hydrochloric acids, have a tendency to corrode
tubing, casing, and equipment both on the surface and downhole,
especially at elevated temperatures. Another problem is that when
acids are pumped into a well, they may cause scale to flake from
the upper wellbore and settle and plug the well at a lower level.
Another problem associated with conventional acidizing systems is
that they can pose handling and/or safety concerns due to the
reactivity of the acid.
[0006] Various methods of generating a thermally activated
acidizing solution based on latent organic acids such as through
the use of hydrolysable esters have been previously developed.
These methods suffer from the limitations of generating an organic
acid, which by their nature, is a weak acid that may only partially
disassociate in a solution. This may limit the dissolving power of
the solution and preclude the ability to generate silica dissolving
acids such as hydrofluoric acid from fluoride salts.
[0007] It is desirable to develop a method acidizing a wellbore or
a subterranean formation using a solution that generates a strong
acid that does not suffer from any of these conventional
drawbacks.
SUMMARY
[0008] The present disclosure relates generally to thermally
activated strong acids. More specifically, in certain embodiments,
the present disclosure relates to compositions capable of
generating strong acids downhole and associated methods.
[0009] In one embodiment the present disclosure provides an
acid-generating fluid comprising a thermally activated strong acid
precursor.
[0010] In another embodiment, the present invention provides a
method comprising: providing an acid-generating fluid that
comprises a thermally activated strong acid precursor and placing
the acid-generating fluid into a subterranean formation.
[0011] In another embodiment, the present invention provides a
method comprising: providing an acid-generating fluid that
comprises a thermally activated strong acid precursor; placing the
acid-generating fluid into a subterranean formation; generating a
thermally activated strong acid.
[0012] The features and advantages of the present disclosure will
be readily apparent to those skilled in the art. While numerous
changes may be made by those skilled in the art, such changes are
within the spirit of the disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The present invention will be better understood by referring
to the following detailed description of preferred embodiments and
the drawings referenced thereof, in which:
[0014] FIG. 1. is a plot of IR optic data in Example 1 showing the
concentration of the ethylene sulfite and generated hydroxymethane
sulfonic acid;
[0015] FIG. 2 is a plot of IR optic data in Example 2 showing the
concentration of the ethylene sulfite and generated hydroxymethane
sulfonic acid;
[0016] FIG. 3 is a plot of results of IR optic data in Example 3
showing the absorbencies of the components; and
[0017] FIG. 4 is a plot of IR optic data in Example 4 showing the
concentration of the SO.sub.2, trioxane, and generated
hydroxymethane sulfonic acid.
DETAILED DESCRIPTION
[0018] The description that follows includes exemplary apparatuses,
methods, techniques, and/or instruction sequences that embody
techniques of the inventive subject matter. However, it is
understood that the described embodiments may be practiced without
these specific details.
[0019] The present disclosure relates generally to thermally
activated strong acids. More specifically, in certain embodiments,
the present disclosure relates to compositions capable of
generating strong acids downhole and associated methods.
[0020] Some desirable attributes of the methods discussed herein
are that they may be much less corrosive to tubing, casing, and
other equipment both on the surface and downhole than conventional
systems. Another desirable attribute is that they may not free up
deposited scale in the higher reaches of the well systems which can
lead to flaking and plugging. Yet another desirable attribute is
that they may be capable of achieving deeper penetration into the
subterranean formation from the well bore than conventional
systems.
[0021] In certain embodiments, the present disclosure provides an
acid-generating fluid comprising a thermally activated strong acid
precursor. As used herein, the term thermally activated strong acid
refers to a strong acid that has been generated by heating an
essentially pH neutral aqueous solution containing a thermally
activated strong acid precursor from a stable temperature. As used
herein, the term strong acid refers to an acid having a having a pH
value of less than 1 and/or one that is capable of complete
ionization.
[0022] In certain embodiments, the thermally activated strong acid
precursor may comprise one or more compounds, and/or one or more
precursors of such compounds, that react together to form thermally
activated strong acids. In certain embodiments, the compounds
capable of reacting together to form thermally activated strong
acids may be SO.sub.2 and/or carbonyls. In certain embodiments, the
thermally activated strong acid precursors may comprise SO.sub.2
precursors (or SO.sub.2) and/or organic carbonyl precursors (or
organic carbonyls).
[0023] Examples of suitable SO.sub.2 precursors include sulfones
and sulfites. Examples of suitable sulfones include sulfone adducts
of butadiene, sulfone adducts of piperylene, and sulfone adducts of
isoprene. Examples of suitable sulfites include sulfite esters such
as ethylene sulfite, dimethyl sulfite, diethyl sulfite,
1,2-propylene sulfite, and 1,3-propylene sulfite.
[0024] Examples of suitable carbonyl precursors or carbonyls
include any carbonyl (or precursor that generates a carbonyl)
capable of reacting with SO.sub.2 to form an alpha-hydroxy sulfonic
acid. In certain embodiments, the carbonyls may comprise from 1 to
7 carbon atoms. Examples of suitable carbonyls (or precursors
thereof) include aldehydes, metaldehyde, trioxane, formaldehyde,
acetaldehyde, propionaldehyde, n-butyraldehyde, butyraldehyde,
glycolaldehyde, glyceraldehyde, glyoxal, benzaldehyde,
cyclohexanone, acetone, chloroacetone, paraformaldehyde,
polyoxymethylene, and any precursor or combination thereof. Other
examples of suitable carbonyls (or precursors thereof) include
ketones, acetone, acetal, ketal, cyclic acetals, methyl ethyl
ketone, mesityl oxide, methyl i-butyl ketone, and any precursors or
combination thereof. In certain embodiments, the carbonyl may
include a mixture of ketones and/or aldehydes (or precursors
thereof) with or without alcohols that may be converted to ketones
and/or aldehydes.
[0025] In certain embodiments, the acid generating fluid may have
an essentially neutral pH. In certain embodiments, the acid
generating fluid may have a pH in the range of from 6.5 to 7.5. In
other embodiments, the acid generating fluid may have a pH in the
range of from 6 to 8. In other embodiments, the acid generating
fluid may have a pH of in the range of from 3 to 9.
[0026] In certain embodiments, the thermally activated strong acid
precursors may be activated to produce an alpha hydroxy sulfonic
acid. In certain embodiments, the thermally activated strong acid
precursors may be activated to produce a blend of alpha hydroxyl
sulfonic acids. In certain embodiments, the alpha hydroxyl sulfonic
acid may be of the general formula:
##STR00001##
where R.sub.1 and R.sub.2 are individually hydrogen or hydrocarbyl
with up to about 9 carbon atoms that may or may not contain oxygen.
In certain embodiments, the alpha hydroxyl sulfonic acid may
comprise hydroxy methyl sulfonic acid and/or hydroxyl ethyl
sulfonic acid. In certain embodiments, the alpha hydroxyl sulfonic
acid, or blend thereof, may have a pH of less than 1. In other
embodiments, the alpha hydroxyl sulfonic acid, or blend thereof,
may a pH of between 1 and 2.
[0027] As used herein, the term "activated" refers to the process
in which the one or more thermally activated strong acid precursors
releases strong acid components and then those strong acid
components reacts with another component and water to form a
thermally activated strong acid. Additionally, the term activated
also refers to the process in which the one or more components of
the thermally activated strong acid react with each another and
water to form the thermally activated strong acid.
[0028] In certain embodiments, the one or more precursors of the
components of the thermally activated strong acid may release the
components when exposed to a certain temperature. In certain
embodiments, the one or more precursors of the components of the
thermally activated strong acid may release the components when
hydrolyzing in water. For example, trioxane is readily soluble in
water and stable at ordinary temperatures, but when warmed to
approximately 80.degree. C. this compound hydrolyzes or decomposes
to generate formaldehyde. Similarly, when aqueous metaldehyde
solutions are warmed they may generate acetaldehyde. If the aqueous
solutions contained SO.sub.2 or a precursor thereof, the warmed
solution may immediately form an alpha hydroxyl sulfonic acid. In
certain embodiments, the one or more precursors of the components
of the thermally activated strong acid may release the components
at room temperature.
[0029] In another example, an aqueous solution of ethylene sulfite
and formaldehyde, which is essentially pH neutral is warmed, the
ethylene sulfite may hydrolyze with water present to make SO.sub.2
and ethylene glycol, and SO.sub.2 and formaldehyde may combine with
water to make alpha hydroxyl methane sulfonic acid.
[0030] In certain embodiments, the thermally activated strong acid
precursor may comprise a sulfone adduct of butadiene and/or an
aldehyde. In certain embodiments, the amount of sulfolene adduct of
butadiene present in the acid-generating fluid may be an amount
sufficient to generate a strong acid in the fluid with a
concentration of from 0.05% to 20%, from 0.1% to 10%, or from 0.5%
to 5% by weight of the acid-generating fluid. In certain
embodiments, the amount of aldehyde present in the acid-generating
fluid may be an amount sufficient to generate a strong acid in the
fluid at a concentration of from 0.05% to 20%, from 0.1% to 10%, or
from 0.5% to 5% by weight of the acid-generating fluid. In certain
embodiments, the ratio of sulfolene adduct of butadiene to aldehyde
present in the acid-generating fluid may be from 10:1 to 1:10.
[0031] In certain embodiments, for example when thermally activated
strong acid precursors comprises a sulfone adduct, the
acid-generating fluid may comprise a dieneophile. The dieneophile
may be capable of reacting with a generated diene from the sulfone
adduct to from a Diels-Alder adduct. Prudent selection of the
dieneophile may result in a di-acid chelating agent. Examples of
such suitable dieneophiles include dimethylmaleate. In certain
embodiments, the amount of dieneophile present in the
acid-generating fluid may be in the range of from fractional to
excess molar amounts to the amount of the sulfone adduct employed.
In certain embodiments, the dieneophile may be present in an equal
molar concentration of the sulfone adduct.
[0032] In certain embodiments, the thermally activated strong acid
may comprise a sulfite ester and/or a carbonyl. In certain
embodiments, the amount of sulfite ester present in the
acid-generating fluid may be an amount sufficient to generate a
strong acid in the fluid with a concentration of from 0.05% to 20%,
from 0.1% to 10%, or from 0.5% to 5% by weight of the
acid-generating fluid. In certain embodiments, the amount of
aldehyde present in the acid-generating fluid may be may an amount
sufficient to generate a strong acid in the fluid with a
concentration of from 0.05% to 20%, from 0.1% to 10%, or from 0.5%
to 5% by weight of the acid-generating fluid. In certain
embodiments, the ratio of sulfite ester to carbonyl present in the
acid-generating fluid may be from 10:1 to 1:10.
[0033] In certain embodiments, the acid-generating fluid may
comprise a base fluid. Examples of suitable base fluids include
water. In certain embodiments, the base fluid may be present in the
acid-generating fluid in an amount in the range of from 0.01% to
99% by weight of the acid-generating fluid.
[0034] In certain embodiments, the acid-generating fluid may be an
emulsion. In certain embodiments, the emulsion may comprise an
oil-in-water emulsion or a water-in-oil emulsion. In certain
embodiments, the one or more thermally activated strong acid
precursors may be in the aqueous portion of the emulsion or the
non-aqueous portion of the emulsion. In other embodiments, one
thermally activated strong acid precursors may be in the aqueous
portion while the other may be in the non-aqueous portion. In other
embodiments, the acid-generating fluid may be a homogenous
solution.
[0035] In certain embodiments, the acid generating fluid may be a
component of a fluid loss control pill. In certain embodiments, the
fluid loss control pill may the acid generating fluid and a gelling
agent.
[0036] In certain embodiments, the acid generating fluid may be
present in the fluid loss control pill in an amount in the range of
from 0.01% to 99% by weight of the fluid loss control pill. In
certain embodiments, the amount of acid generating fluid present in
the fluid loss control pill may be an amount sufficient to generate
enough alpha hydroxyl sulfonic acid to completely break the fluid
loss control pill once activated.
[0037] In certain embodiments, the gelling agent may comprise any
gelling agent discussed in U.S. Pat. No. 7,795,186, the entirety of
which is hereby incorporated by reference. In certain embodiments,
the gelling agent may be present in the fluid loss control pill in
an amount sufficient to form a gel with the acid generating fluid.
In certain embodiments, the fluid loss control pill may be a
homogenous mixture.
[0038] In certain embodiments, the present invention provides a
method comprising: providing an acid-generating fluid that
comprises a thermally activated strong acid precursor and placing
the acid-generating fluid into a subterranean formation.
[0039] In certain embodiments, the acid-generating fluid may be
placed into the subterranean by any conventional means. Examples of
suitable subterranean formations include any subterranean formation
with a temperature high enough to activate the thermally activated
strong acid. In certain embodiments, the subterranean formation
temperature may at room temperature or above 40.degree. C., above
50.degree. C., above 60.degree. C., above 70.degree. C., above
80.degree. C., above 90.degree. C., above 100.degree. C., above
110.degree. C., or above 120.degree. C. Examples of conventional
means include introducing the acid-generating fluid as a fluid, an
emulsion, or a pill. In certain embodiments, one or more thermally
activated strong acid precursors may be present in the subterranean
formation before the acid-generating fluid is placed into the
subterranean formation. In certain embodiments, water may be
present in the subterranean formation before the acid-generating
fluid is placed into the subterranean formation.
[0040] In certain embodiments, the method may further comprise
generating a thermally activated strong acid. In certain
embodiments, generating a thermally activated strong acid may
comprise activating the thermally activated strong acid precursors
to form the thermally activated strong acid.
[0041] In certain embodiments, a thermally activated strong acid
precursor present in the acid-generating fluid may react with a
thermally activated strong acid precursor previously in the
subterranean formation and water to form the thermally activated
strong acid. In certain embodiments, the thermally activated strong
acid precursor present in the acid-generating fluid may release a
component of the thermally activated strong acid due to the
temperature in the subterranean formation. For example, when an
acid-generating fluid comprising an SO.sub.2 precursor such as a
sulfone or sulfite and a carbonyl is introduced into a subterranean
formation at a temperature above 80.degree. C., the SO.sub.2
precursor may release the SO.sub.2 and the SO.sub.2 may react with
the carbonyl to form an alpha hydroxy sulfonic acid. Alternatively,
when an acid-generating fluid comprising a carbonyl precursor and
SO.sub.2 is introduced into a subterranean formation containing at
a temperature above 80.degree. C., the carbonyl precursor may
release the carbonyl and the carbonyl may react with the SO.sub.2
form an alpha hydroxy sulfonic acid.
[0042] In certain embodiments, two thermally activated strong acid
precursors present in the acid-generating fluid may release
components of the thermally activated strong acid and those
components may then react with each other and water in the
subterranean formation to form the thermally activated strong acid.
In certain embodiments, the two thermally activated strong acid
precursors present in the acid-generating fluid may release a
component of the thermally activated strong acid due to the
temperature in the subterranean formation. For example, when an
acid-generating fluid comprising an SO.sub.2 precursor such as a
sulfone or sulfite and a carbonyl precursor is introduced into a
subterranean formation at a temperature above 80.degree. C., the
SO.sub.2 precursor may release the SO.sub.2, the carbonyl
precursors may release the carbonyl, and the SO.sub.2 may react
with the carbonyl to form an alpha hydroxy sulfonic acid.
[0043] In embodiments, where the acid-generating fluid comprises a
sulfone addict of butadiene, the sulfone addict of butadiene may
release butadiene when activated. In such embodiments, a dienophile
present in the acid-generating fluid or the subterranean formation
may react with butadiene to form a diacid. In certain embodiments,
where the acid-generating fluid comprises a sulfite ester, an
alcohol such as ethylene glycol may be released when the sulfite
ester is activated.
[0044] In certain embodiments, the formation of the thermally
activated strong acid may be an autocatalytic reaction. In certain
embodiments, calcium carbonate or other base, such as KOH, NaOH,
NH.sub.4OH, may be added to the reaction as part of the
acid-generating fluid or be present in the subterranean formation
to slow the reaction. In certain embodiments, the base may be
present in the acid-generating fluid in an amount in the range of
from 0% to 5% by weight of the acid-generating fluid.
[0045] In certain embodiments, the acid-generating fluid may be
placed into the subterranean as part as a fluid loss control pill.
In certain embodiments, the acid-generating fluid may be allowed to
break the fluid loss control pill after being introduced into the
subterranean formation.
[0046] To facilitate a better understanding of the present
invention, the following examples of certain aspects of some
embodiments are given. In no way should the following examples be
read to limit, or define, the scope of the invention.
EXAMPLES
Example 1--Ethylene Sulfite and Formalin
[0047] At room temperature, 15.01 grams of ethylene sulfite
(Sigma-Aldrich lot# BCBB370V) and 11.55 grams of formalin
(Sigma-Aldrich, ACS Reagent, 37% w in water 10-15% wt. methanol as
stabilizer, Lot# SHBB0285) were add to 129.95 grams of water and
stirred to produce a homogenous, clear solution. This solution was
loaded into a 300 ml autoclave fitted with IR optics. Stirring at
750 rpm was initiated. The mixture was held at ambient conditions
(.about.20 C) for about 20 minutes with no obvious sign of sulfite
hydrolysis or HMSA production. The reactor was then heated to
50.degree. C. over 6 minutes and then held at temperature for 30
minutes with no obvious sign of sulfite hydrolysis or HMSA
production. The mixture was heated to 80.degree. C. over 5 minutes.
After approximately 15 minutes at 80.degree. C. the ethylene
sulfite began to significantly react away and HMSA started to be
produced. The reactions were seen to be complete approximately 2
hours after reaching 80.degree. C. The reactor was cooled and the
run terminated after about 4 total hours from the start of the run.
The reactor contents were sampled and 4H NMR confirmed that 15.6 g
of HMSA was produced (10% w) during the course of the reaction and
that all of the ethylene sulfite and aldehyde that were initially
charged had been consumed. A mole of ethylene glycol was also made
for each mole of ethylene sulfite hydrolyzed. A plot of the IR
optic data showing the concentration of the ethylene sulfite and
generated hydroxymethanesulfonic acid are shown in FIG. 1. As can
be seen in FIG. 1, the generation of acid looks to be an
autocatalytic reaction by the shape of the curve. Note that the
shifts in baseline absorbance between temperatures are uncorrected
in the graphs. They are caused by a combination of IR crystal
refractive index changes and solution molarity changes, which are
both temperature dependent.
Example 2--Dimethyl Sulfite and Formalin and CaCO.sub.3
[0048] At room temperature, 15.03 grams of dimethyl sulfite
(Sigma-Aldrich Lot# MKBJ9974V), 11.58 grams of formalin
(Sigma-Aldrich, ACS Reagent, 37% wt. in water 10-15% wt. methanol
as stabilizer, Lot# SHBB0285), and 3.50 grams of CaCO.sub.3 were
add to 130.12 grams of water and stirred to produce a slurry. This
slurry solution was loaded into a 300 ml autoclave fitted with IR
optics. The mixture was directly heated to 100.degree. C. and held
there for 267 minutes at which point the reaction was terminated.
The reactor contents were sampled after cooling. The reactor
contents were found to be a clear colorless solution. 1H NMR
confirmed that HMSA/HMSA salt was produced during the course of the
reaction with >96% of theoretical anion recovered. All of the
dimethyl sulfite and aldehyde had been consumed during the course
of the reaction, along with the initially insoluble CaCO.sub.3. A
plot of the IR optic data showing the concentration of the ethylene
sulfite and generated hydroxymethane sulfonic acid (or the
Ca.sup.2+ salt of the acid as they both have the same IR signature)
are shown in FIG. 2. As can be seen in FIG. 2, the generation of
acid is slow until the CaCO.sub.3 is consumed at which point the
reaction turns into an autocatalytic reaction. Note that the shifts
in baseline absorbance during the temperature ramp from ambient to
100.degree. C. is uncorrected in the graphs. The main change is
caused by a combination of IR crystal refractive index changes and
solution molarity changes, which are both temperature
dependent.
Example 3--1,3,5-Trioxane and 3-Sulfolene
[0049] At room temperature, 4.82 grams of trioxane and 20.0 grams
of 3-sulfolene were added to 155 grams of water and stirred to
produce a homogenous, near clear solution. This solution was loaded
into a 300 ml autoclave fitted with IR optics. The mixture was
heated to 80.degree. C. and held there for 90 minutes with no
changes in the in situ IR spectra. The mixture was then heated from
80.degree. C. to 130.degree. C. and then held there. The results of
the IR optic data showing the absorbencies of the components are
shown in FIG. 3. As can be seen in FIG. 3, no acid was observed to
be generated at 80.degree. C. As indicated by a drop in the
absorbance of trioxane, this trimer began to decompose to
formaldehyde at about 105.degree. C. The 3-sulfolene slowly began
to decompose at above 100.degree. C. to SO.sub.2 and butadiene. The
IR bands of hydroxymethane sulfonic acid increase at temperatures
above 100.degree. C., indicating formation.
Example 4--SO.sub.2 and Trioxane
[0050] At room temperature into a 600 ml Parr Autoclave fitted with
in situ IR optics was loaded a solution of 7.29 grams trioxane and
250 ml of water. The reactor was sealed and 15.5 grams of SO.sub.2
was added via blow case injector. The solution was heated to
50.degree. C. and no change was observed in the infrared spectra
with IR bands of all major components remaining unchanged. The
solution was then heated to 80.degree. C., again no change was
observed. The solution was then heated to 100.degree. C. without
any observed change. The solution was then heated to 130.degree. C.
and the formation of hydroxyl methane sulfonic acid was observed. A
plot of the IR optic data showing the concentration of the
SO.sub.2, trioxane, and generated hydroxymethanesulfonic acid are
shown in FIG. 4.
Example 5--Pill Breaking
[0051] A first, second, and third fluid loss pill containing the
strong acid generating internal breaker components and a
corresponding blank containing no strong acid internal breaker
components were manufactured from the same batch of materials.
First, 96.0 g of gelling agent (WG-33, Halliburton) and 80 ml of
propylene glycol were added to approximately 1800 ml of 14.3 pound
per gallon calcium bromide brine (TETRA Technologies, Inc.) in a
high speed blender (VitaMix Professional Series 750). The mixture
was stirred for 2-3 minutes prior to adding 10 ml of 37% wt.
hydrochloric acid and then stirred for an additional fifteen to
thirty minutes. The mixture was then split into three portions with
1564.5 g for internal breaker addition, 1564.5 g for internal
breaker addition, and the remaining non cross-linked pill as a
retained sample. For the internal breaker sample, 43.37 g of
3-sulfolene (Aldrich, 98% lot # MKBN9972V), and 11.15 g of
paraformaldehyde (Sigma-Aldrich, lot #090M1738V) were added and
mixed until homogeneous. The pill was completed by adding 3.6084 g
of cross-linking agent (CL-30, Halliburton) slurried in 10 ml of
water. This was blended until the vortex closes. For the blank
sample, no internal breaker was added and the same procedure was
followed. The two pills were then distributed for testing using
different temperatures.
[0052] The first fluid loss pill containing the strong acid
generating internal breaker and a corresponding blank was heated to
60.degree. C. The second fluid loss pill containing the strong acid
generating internal breaker and corresponding blank was heated to
85.degree. C. The third fluid loss pill containing the strong acid
generating internal breaker and corresponding blank was heated to
110.degree. C. It was observed that the third fluid loss pill
containing the strong acid generating internal breaker was
completely broken to a free flowing liquid in three hours. It was
also observed that the second fluid loss pill containing the strong
acid generating internal breaker was completely broken to a free
flowing liquid between 24 and 48 hours. It was also observed that
the first fluid loss pill containing the strong acid generating
internal breaker remained an unbroken gelatinous mass after 114
hours. The three corresponding blanks at the three given
temperatures also remained unbroken gelatinous masses after 114
hours.
Example 6--Pill Breaking Under Ambient Conditions
[0053] 24.55 g of gelling agent (WG-33, Halliburton) was mixed with
20 ml of propylene glycol and added to approximately 450 ml of 14.3
pound per gallon calcium bromide brine (TETRA Technologies, Inc.)
in a high speed blender (VitaMix Professional Series 750). The
mixture was stirred for 2-3 minutes prior to adding 2.5 ml of 37% w
hydrochloric acid and stirred for an additional fifteen to thirty
minutes. 2.03 g of sodium hydroxide dissolved in 2.79 g of water
was added in two aliquots and stirred until homogeneous to increase
the material pH (.about.3-4 range as measure by pH paper) prior to
the addition of 50.4 g of ethylene sulfite (Beta Pharma Scientific,
Lot # E130702) and 13.99 g of paraformaldehyde (Sigma-Aldrich, lot
#090M1738V). It should be noted that if the pH is not increased,
the ethylene sulfite (or other sulfites tested) will begin to react
immediately and the pill will not cross-linked effectively. The
pill was completed by adding 1.8 g of cross-linking agent (CL-30,
Halliburton) slurried in 10 ml of water. This was blended until the
vortex closed.
[0054] The fluid loss pill with strong acid generating internal
breaker components was then allowed to sit at ambient conditions
(.about.23.degree. C.) overnight. It was observed that the fluid
loss pill containing the strong acid generating internal breaker
was completely broken to a free flowing liquid in less than 21
hours.
[0055] While the embodiments are described with reference to
various implementations and exploitations, it will be understood
that these embodiments are illustrative and that the scope of the
inventive subject matter is not limited to them. Many variations,
modifications, additions and improvements are possible.
[0056] Plural instances may be provided for components, operations
or structures described herein as a single instance. In general,
structures and functionality presented as separate components in
the exemplary configurations may be implemented as a combined
structure or component. Similarly, structures and functionality
presented as a single component may be implemented as separate
components. These and other variations, modifications, additions,
and improvements may fall within the scope of the inventive subject
matter.
* * * * *